DENVER, March 8 (Reuters) - School officials who banned a6-year-old transgender girl in Colorado from using the girls'lavatory have declined to take part in mediation of the civilrights complaint brought by her parents, the two sides said onFriday.

First-grader Coy Mathis, who was born male but identifies asfemale, had been using the girls' restroom at EaglesideElementary School near Colorado Springs until late last year,when the principal informed her parents she would no longer bepermitted access to the girls' facilities.

Instead, she was restricted to using either the boys'restrooms or gender-neutral facilities reserved for employees orthose in the school's health room, her parents said.

The parents and lawyers representing the family urged theprincipal to reconsider, contending that singling out theirdaughter as the only girl in the school barred from using thegirls' bathrooms was stigmatizing and psychologically damaging.

They also asserted that the restriction violated the state'santi-discrimination laws and asked school officials to at leastmaintain the status quo -- allowing Coy to keep using the girls'restroom -- until both sides had a chance to discuss the issue.

But responding to the family by letter in late December, theschool district defended its actions as consistent with statelaw and refused to back down.

The district gave little explanation of its position exceptto state that it "took into account not only Coy but otherstudents in the building, their parents, and the future impact aboy with male genitals using a girls' bathroom would have as Coygrew older."

The girl's parents, Kathryn and Jeremy Mathis, then tooktheir daughter out of Eagleside to home-school her and filed acomplaint last month with the Colorado Civil Rights Commission.

The family's lawyer, Michael Silverman, said the first stepin seeking to resolve such a complaint is to see if both sideswill agree to mediation, which the Fountain-Fort Carson SchoolDistrict declined to do.

"We are shocked that her school will not even meet to talkabout this so that Coy can quickly return to school," saidSilverman, executive director of the Transgender Legal Defenseand Education Fund. He said the commission would now open alengthy inquiry into the case.

The school district, which has until mid-March to formallyanswer charges in the complaint, acknowledged having declinedmediation, a step it said "would be unproductive." But it saidthe parents had refused to meet with school officials when thematter first surfaced in December.

"The parents consistently indicated ... that they would filea discrimination charge if the district did not completelyacquiesce to their demands," the district said in a statement.It also said the family had been unwilling to discuss"reasonable proposals" to resolve the dispute.

The parents' complaint asserts that the district violated astate law that bars schools from denying individuals access topublic accommodations because of their sexual orientation ortransgender status.

They also have cited anti-discrimination regulations issuedby the state Civil Rights Commission that specifically requireschools to allow transgender students access to"gender-segregated facilities that are consistent with theirgender identity," including restrooms, locker rooms anddormitories.

The parents said in a statement on Friday that in limitingtheir daughter to the boys' lavatory, a gender-neutral employeerestroom or the bathroom in the school's health clinic thedistrict was inviting mistreatment of their daughter byclassmates.

"Coy is not sick, she is not an adult, and she is not aboy," the statement said. "We are saddened that her school willnot even come to the table to talk about this issue."

But the district said the proper forum to discuss the issueis in the "process initiated ... by the parents," and not in thenews media.